Ripple Pond

Ripple Pond is a sheet of still water and nothing to do but disturb it. Every tap drops a stone, sending a ring travelling outward across the surface. Drag and you trail a continuous wake behind your finger. Rings reflect off the edges of the pond and come back, and when two rings meet they pass straight through each other, adding where crests line up and cancelling where a crest meets a trough. That interference is the reason a few taps in different places produce a pattern far more complicated than the taps themselves.

This is a real wave simulation rather than a set of expanding circles. Each point on the surface is pulled toward the average height of its neighbours and away from where it was a moment before, which is the discrete form of the wave equation. Waves therefore travel at a consistent speed, bend correctly, and lose energy gradually instead of being faded out on a timer. The Calm slider controls how quickly that energy bleeds away — turn it down and ripples persist for a long time, building into a choppy surface that takes a while to settle.

The surface is shaded by its slope rather than its height, which is what gives it the bright rolling sheen of water catching light instead of looking like a flat heat map. Rain drops stones continuously at random across the pond, which is worth leaving running — the overlapping rings never settle into a repeating pattern. Drop size is adjustable, Still freezes everything back to glass, and there is no score or objective of any kind. Free in the browser, nothing to install.